Planchón-Peteroa: aerial view towards the east, showing the arrangement of the craters, the currently active south-western crater and deposits of ash on the icecap and snow. SERNAGEOMIN image, taken on 7 September 2010.

The Chilean state geological service SERNAGEOMIN has issued a new bulletin today on the activity at Planchón-Peteroa, reporting the outcome of an overflight of the volcanic complex which took place yesterday:

On the basis of the overflight of the area of the Planchón-Peteroa volcanic complex carried out on 7 September by SERNAGEOMIN personnel it can be concluded that Planchón volcano is maintaining eruptive activity with weak explosions, possibly of phreatomagmatic origin, similar to minor phases of the eruption recorded in 1991.

The currently active crater is the south-western, which has for several years usually shown persistent fumarolic activity.

The current eruptive activity shows local accumulations of ash in the area within 10 km of the volcano and no alterations have been observed in the glaciers of the volcanic complex.

The activity is described as consisting of ‘discrete pulses of gases and fine ash with a frequency of between 40 and 60 seconds’. These emissions create a ‘weak eruptive column of grey colour’ rising up to 200 metres above the crater, which then disperses towards Argentine territory, to the east of the volcano. The current activity at Planchón-Peteroa, according to SERNAGEOMIN, does not present a hazard to the local population, but continuous monitoring of the volcano will be carried out for as long as the activity continues. Planchón-Peteroa is currently at ‘alert level 4 Yellow’.

Planchón-Peteroa: aerial view towards the south-east, showing the western flank of the Planchón (north)-Peteroa (south) volcanic complex, with prominent ash deposits on the icecap and snow. SERNAGEOMIN image, taken on 7 September 2010.

Planchón-Peteroa: aerial view towards the east, showing the low altitude of the eruption column and the plume dispersing towards the east-south-east, over Argentine territory. SERNAGEOMIN image, taken on 7 September 2010.

Mount Sinabung in northern Sumatra continues to be highly active. The Indonesian Volcanological Authority (VSI) has confirmed another eruption in the early hours of this morning: the VSI reports that ‘shallow earthquakes’ from around 21:00 on 6 September were followed by an explosive eruption beginning at 00:23 and lasting until 00:38 on 7 September (all times are local). ‘Thick black smoke’ reached an altitude of approximately 5000 m above the crater, with the plume being blown towards the south-east. Darwin VAAC is reporting ash from Sinabung at FL250 (25,000 ft / 7.5 km altitude) – i.e. the 5000 m altitude of the emissions plus the height of Sinabung itself, which is about 2.5 km.

Chief Government volcanologist Surono is quoted by Reuters as describing this as ‘the biggest eruption yet’. A VSI spokeswoman told Malaysia’s Bernama news agency that the sound of the eruption was audible 8 km away from the volcano. Volcanic deposits of up to 1 cm thickness have been reported in nearby villages, and the ashfall situation has been made worse by heavy rain in the area overnight. Indonesian President Susilo Bambang Yudhoyono, who was making an official visit to the area (with entourage), was forced to stay there when his flight back to Jakarta was delayed by this latest eruption.

There are no reports of deaths or injuries from the latest activity, but there is concern for local villagers and farmers who have returned to the evacuated zone around the volcano to safeguard their properties.

For those who can read Indonesian, a PDF briefing on the eruption is available from the VSI’s publications archive, and the regular briefings on Sinabung’s activity can be downloaded as PDF documents from a table labelled ‘Perkembangan Kegiatan G. Sinabung’ on the VSI main page. The latest briefing, released at 06:00 on 7 September, can be downloaded here.

UPDATE. An Indonesian Geological Service webcam for Sinabung can be found via this page: click on the weird little eye in the lower part of the satellite image and the webcam view will pop up (or just click here for a direct link to the image – manual refresh required).

Some highlights from the last week of volcanic activity courtesy the Global Volcanism Program and Sally Kuhn Sennert, including more seismic restlessness and ash venting at Soufrière Hills and some big bangs at Stromboli:

Eruption of the old volcano of Eyafjeld Jokkul in Iceland, in December 1821

The remarkable fall of the barometer which took place almost simultaneously throughout all Europe, in the month of December, 1821, and which in some cases was accompanied with an agitation of the magnetic needle, brought many persons to conjecture that some tremendous convulsion of nature must have visited some part of the globe. This conjecture has at last been verified by a volcanic eruption of the old volcano of Eyafjeld Jokkul, which has been in a quiet state since the year 1612.

This mountain, otherwise called Mount Hecla, is about 5666 feet in height. It is nearly equidistant from Kolla and Hecla, and is the southernmost of the chain where a dreadful eruption broke out about the middle of the last century.

On the 19th December, 1821, the eruption began. The crater was formed at the distance of five miles from the minister’s house at Holt, and discharged itself through the thick mass of ice that enveloped it, and which is never melted. The ice was dispersed in every direction, of which one mass, 18 feet high, and 60 feet in circumference, fell towards the north. A number of stones, of different sizes, rolled down the mountain, accompanied with a noise like thunder; and this was immediately followed by a discharge of an enormous and lofty column of flame, which illuminated the whole country, and allowed the people in Holt to read as perfectly within their houses at night as if it had been day. Ashes, stones, gravel, and heavy masses of rock, some of which weighed about 50 lbs, were thrown up, and one of these last was found at the distance of five miles from the crater. On the day immediately following the eruption, a great quantity of fine greyish-white powder of pumice was discharged, and carried about by the wind so as to fall like snow, through every opening. It exhaled a disagreeable smell of sulphur, brought on affections in the eyes, and occasioned diseases among the sheep in Vaster Eyafjeld and Oster Landoe.

On the 25th of December, a violent storm raged from the south, and by the united action of the wind and rain, the fields were cleaned of the sulphurous dust which had covered them. On the 26th and 27th of December, there was a heavy storm from the north-east, and the barometer, which had been gradually falling since the 18th December, when it was 29° 16, had reached, on the 26th December, its lowest point at 28° 49. It is a curious fact, however, that on the 8th of February, the barometer fell to 27° 25, a time when no earthquake was felt, and no apparent change had taken place in the eruption. On the 18th of February, the barometer, which had been at 29° 42 on the 11th fell to 27° 72. So late as the 23d of February, the Eyafjeld Jokkul emitted smoke greatly resembling the steam of boiling water; and some persons were of the opinion that the mountain had decreased, and was lower near the crater, as it evidently appeared to be when viewed in a direction from north to south.

It is stated that the water in the rivers that flow from the Jokkul and the surrounding mountains, had been considerably enlarged during the first day’s eruption. A constant rumbling noise was heard in the vicinity of the volcano, attended occasionally by a dreadful crash, as if the immense masses of stones and ice were on the eve of all being precipitated down the mountain.

Other two volcanoes to the east, in the mountains of Kolla and Oraefa Jokkul, are said to have broken out, but no certain information has been received on that subject.

The vessel which brought the account of the volcanic eruption to Copenhagen, left Iceland on the 7th of March and it is reported that the sailors, when at sea, again saw a violent fire in the direction of the volcano.

Overall, ‘More explosive activity and ash production than was observed yesterday. Progression of the lava seems to be slower than yesterday. Presently there are no indications that the eruption is about to end’.

Further airspace closures over the British Isles will take effect tomorrow because of the continuing presence of dangerous levels of volcanic ash from Eyjafjallajökull (click here for London VAAC ash advisory issued at 18:30Z today, in graphic form). At present the closures are planned to affect Scotland and Northern Ireland, but as the ash moves east and south other parts of Britain may be affected.

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